1. Field of the Invention
The invention generally relates to a baffle plate configuration of an internal combustion engine, more particularly, to a baffle plate configuration of an internal combustion engine that prevents adverse effects on a flow of lubricant in a pan caused by piston pumping air generated above the baffle plate.
2. Description of the Related Art
A technology in which a baffle plate is provided to separate rotational members arranged on or near a crankshaft, for example, connecting rods, from lubricant in a pan is disclosed in Japanese Utility Model Application Publication No. JP-U-5-7917. It is an object of the technology to prevent the rotational members and lubricant from interfering each other.
Piston pumping air (that is, blowby gas) generated above the baffle plate tends to enter the pan through the end of the baffle plate in one side of the crankshaft in the axial direction thereof, which is opposite to the other side where, owing to some structural reason such as a timing chain being provided therein, a large amount of lubricant returns to the pan. This tendency becomes stronger as the displacement of the internal combustion engine becomes larger, because the amount of piston pumping air accordingly increases. In this case, the lubricant that is returning to the pan through the baffle plate in the one side of the crankshaft collides with the piston pumping air that is entering the pan through the baffle plate in the other side of the crankshaft. Therefore, the lubricant cannot smoothly return to the pan.
Further, in terms of protection of pedestrians and arrangement of accessories, it is preferable that the overall height of an engine be reduced by reducing the height of the shallow depth portion of a pan. However, when the overall height of the engine is thus reduced, it is more likely that lubricant returning to the pan through the baffle plate in the one side of the crankshaft collides with piston pumping air entering the pan through the baffle plate in the other side of the crankshaft. In consideration of this, a technology that enables lubricant to return smoothly to the pan has been desired.
Moreover, when piston pumping air enters the pan through the baffle plate in the other side of the crankshaft, the following problems, for example, arise: (1) lubricant is further quickly deteriorated as a result of being stirred by the piston pumping air entering the pan; (ii) the temperature of the lubricant increases; (iii) the amount of lubricant that is atomized by the collision between lubricant and piston pumping air and then taken away by the piston pumping air increases; and (iv) the ratio of air bubbles in lubricant increases.